Waterfowl Communities in the Northern Plains

Redhead

Redhead. -- The redhead achieves highest average densities in the parkland of the Prairie Provinces and in the Prairie Pothole Region of the Dakotas, and the stratum containing the Woodworth Study Area had average densities in the highest quartile. Continental populations of redheads showed no trend over the 25-year period, whereas those at Woodworth increased markedly after the mid-1970s (Fig. 11). The increased numbers of diving ducks and ruddy ducks in the Woodworth Study Area, in contrast to declines continentally, may reflect an increase in emergent vegetation in wetlands on the study area. These species most frequently nest over water in such vegetation, which increased after several years once grazing in the area had ceased. Dabbling ducks, on the other hand, ordinarily nest in upland vegetation and their numbers therefore would not be affected closely by the emergent vegetation.

Redhead numbers at Woodworth did not correspond very closely to those of wetlands and this was similar to what was reported by Johnson and Grier (1988). Although simple correlation coefficients with weather variables were not significant, May precipitation entered the best regression equation.

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